The NRL has offered immunity to Manly officials in exchange for information that could be used as evidence against the club in its salary cap investigation.

Fairfax Media has been told the NRL's integrity unit has approached at least two current Sea Eagles officials suspected of having knowledge of undeclared player payments,and encouraged them to come clean. The officials have been told they can take advantage of a moratorium period in which penalties are waived to encourage full disclosure.

The NSW Organised Crime Squad hasn't been able to prove allegations of match-fixing as part of its own probe, but it has emerged that secret payments in breach of salary cap rules may have been made at the Sea Eagles.

The NRL's integrity unit has spoken to current and former club officials as part of its own investigations following allegations some players received secret cash top-ups in addition to their registered contracts. Several third-party agreements are also being investigated for not being at arm's length from the club or not being properly declared to head office.

Several Manly administrators privately believe the club has not done anything wrong and that Strike Force Nuralda - unable to stand up evidence of matches being thrown - is now acting outside its remit in a bid to justify its initial investigation. However, the NRL believes there is sufficient information to warrant its own probe and is speaking to current and former staffers, some of whom have been told they will have immunity if they fully cooperate.

Under section 16 of the NRL's Code of Conduct – which covers player contract and remuneration matters – "if any Club or person bound by this Code reasonably suspects that a breach of the NRL Rules … has occurred, it is the duty of that Club or person to report that suspected breach to the NRL Integrity and Compliance Unit as soon as possible after forming the relevant suspicion."

Article 54 of the code goes on to state: "For the purpose of encouraging Clubs, Players, Match Officials and Game Participants to voluntarily disclose past and current practices in breach of this Code, the Board may declare, by written notice, a moratorium period during which the making of a voluntary disclosure which might reveal evidence of a breach of this Code will not result in any penalty being imposed upon:

The Club, in any case where the Club makes the disclosure;

The Game Participant, in any case where the Game Participant makes the disclosure;

The Player, in any case where the Player makes the disclosure; or

The Match Official, in any case where the Match Official makes the disclosure."

The moratorium clause is also mirrored in the NRL Contract and Remuneration Rules, which adds that any disclosures made will remain confidential.

Parramatta officials suspected of having knowledge of salary cap cheating were also made aware of the moratorium. Had they come forward from the outset, it's likely a moratorium would have been granted and the officials could have confessed without fear of reprisals.

However, the majority within the blue and gold boardroom denied any knowledge, resulting in the "gang of five" ultimately being sacked by the NSW government. The Eels were also fined and docked 12 competition points, which ended their finals campaign. Only last week, former Parramatta CEO Scott Seward, charged with fraud offences, escaped conviction after cooperating with NRL and police investigations.

There has been a high turnover of staff at Manly and feeder team Blacktown Workers, and NRL officials are in the process of talking to several former employees about their time at the club. The investigation is likely to take at least a month, casting a shadow over the Sea Eagles' finals campaign.

But the dramas haven't derailed their season, with Trent Barrett's side firmly in the running for a top-four spot ahead of Sunday's clash with St George Illawarra.